Controller for electric circuits.



No. 795,958. PATENTED AUG'.1,1905.

RUEDEHGREN.

CONTROLLER FOR ELECTRIC CIRCUIT S.

- APPLICATION rum) 1:20.17. 1904.

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I UNITED STATES PATENT OFFICE.

FRED CEDERGREN, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-HALF TO FRANK S. BETZ, OF CHICAGO, ILLINOIS.

CONTROLLER FOR ELECTRIC CIRCUITS.

Specification of Letters Patent.

Patented Aug. 1, 1905.

Application filed December 1'7, 1904. Serial No. 237,314.

To all whom it may concern:

Be it known that I, FRED OEDERGREN, a citizen of the United States of America, and a resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Controllers for Electric Circuits, of which the following is aspecificat-ion.

This invention relates to controllers for varying the resistance in electric circuits, and has particular application to devices which are intended to receive currents from a plurality of different sources of currents of different intensity or from a single source, such as a primary or secondary battery, in which the intensity of currents given out changes through the deterioration or exhaustion of the batteries.

The main object of my invention is to produce a simple and compact controller of this class whichprovides means for varying the intensity of the current between certain limits and which also provides supplemental means for maintaining the intensity of the current at said limits at a constant strength. I accomplish this object by the'device shown in the accompanying drawings, in which Figure 1 is a plan of a controller constructed according to my invention, the wiring being indicated diagrammatically. Fig. 2 is a section of the same on the line 2 2 of Fig. 1.

In the form shown the controller consists of a graphite rheostat 1 and a governingrheostat 2, connected in series with each other and with the source of current, a milliamperemeter, and a connection to the patient being shown as a shunt between the controller-arm and one end of the graphite rheostat.

In the construction shown in the drawings the disk 4, which is of non-conducting material, such as slate, has mounted on its upper surface a layer or strip 5 of graphite or other conductor of relatively high resistance, which is arranged in the form of an arc of a circle disposed concentrically of the center of the disk 4 and which is of uniform breadth and thickness throughout its length.

on the disk 4 in the insulated sector which lies between the ends of the layer of graphite 5 is an annular series of contact buttons, which are connected to resistance-coils 6, of Wire, in the manner shown in the drawings.

Mounted The coils 6 are shown diagrammatically, it being understood that the wires are in the form of flat coils arranged below the disk 4. The series of coils 6 of the governor 2 is connected at one end with the conductor 7 and is also connected. through the contact-buttons 8, with the disk 9, which is in turn connected with a binding-post 10. The disk 9 hides the buttons 8 and is insulated therefrom except at the brush or projecting part 9, which is of suitable size to bear on one button at a time. The position of the shoe 9 is indicated by a pointer 28 and the graduation on the upper surface of the disk. The edge of the disk is serrated or milled to permit the rotation of the same, and the rotation is limited by the stop 24, which engages the pointer at the limiting positions of the disk. A second binding-post 11, which is in electrical connection with one end of the strip 5 of graphite, connects, by means of a conductor 12, with the battery 13,,or other source of current.

A controller-arm 14 is pivotally mounted in the center ofthe disk 4 and is provided with brushes 15, bearing on the surface of the strip 5. The arm 14 is offset, so that the line of contact of the brush 15 with the strip 5 is substantially radial. By rotating the arm 14 a greater or less length of the strip 5 is brought into the circuit, and the resistance is thus varied. The meter 3 and the patient are connected as a shunt of the circuit in the strip between the controller-arm 14 and the binding-post 10. The terminals at 25 lead to the patient. I usually connect an incandescent lamp 16 between the conductors of the circuit to the patient, so that the current may be tested without being connected to the patient, and when the device receives its current from a dynamo or an electric-light circuita lamp 17 is connected in series therewith.

The controller is provided with a stop 18 for limiting the movement of the arm 14.

This stop is in electric connection with the binding-post 11, so that the strip 5 is cut out of the circuit when the arm 14 is in contact with the stop 18. This assures the operator that all of the strip 5 is out of circuit, and avoids the danger of setting the arm 15 so near, to the terminal 20 of the strip as to burn out part of such strip.

The terminals 20 and 21 of the strip 5 consist of metal strips extending across the entire breadth of the strip 5 and seated in a depression in the disk 4, as shown in Fig. 2. The studs 22 serve as connection for conductors. The terminal 21 is connected to the binding-post 10, so that the current flowing between the arm 14 and the binding-post 10 has two paths, one through the strip 5 and the other through the shuntcircuit to the meter and patient. This arrangement is found to increase the effectiveness of the rheostat 1.

The operation of the device shown is as follows: Then the conductors 12 and 7 are connected with the source of current, the arm 14 is moved into contact with the stop 18, the lamp 16 is put in circuit, and the current is regulated by rotating the disk 9 and varying the resistance by the coils 6 until the meter indicates the desired maximum strength of the current, which is to be delivered to the patient. The arm is then moved to the end 21 of the strip, and after the lamp 16 is cut out and connection to the patient is made, the current is gradually increased by shifting the controller-arm 14 in the direction indicated by the arrow 19. The change of current is thus uniform and takes place without shock to the patient. I

It will be seen that if the device is connected at various times with various sources of current, then resistance may be thrown in or out by means of the governing-rheostat 2, so that the current of maximum intensity may in each case be made to suit the desire of the operator and currents of lesser intensity may be produced by shifting the arm 14:. WVhen the source of current is a battery, the cells are most powerful when new, and continually deteriorate with use. By means of a controller constructed according to my invention the ordinary changes in the current between the maximum and minimum strength desired may be controlled by the main rheostat 1, while the deterioration of the strength of the batteries may be compensated for by reducing the resistance in the governing-rheostat 2. It will thus be seen that batteries of greater strength than just sufiicient to give the maximum desired current may be used by reducing the current by means of the governingrheostat, and thus the cells may be used until too weak to give the desiredmaximum of current even after the rheostat 2 is cut out of the circuit. In this case when the cells are discarded they will have been used for a much longer period than would be the case if the cells were at first of just suflicient intensity to give the desired maximum current with the rheostat 1 and had to be discarded as soon as they were no longer capable of giving such maximum current.

It will be seen that some of the details of the construction shown may be altered without departing from the spirit of my invention.

IVhat I claim as my invention, and desire to secure by Letters Patent, is

1. In a controller, the combination of circular strip of conducting material of high resistance; a controller-arm mounted to rotate on a pivotal axis concentric with said strip, said arm being insulated at the center from the strip and having thereon a shoe having electrical connection with the strip; a sector of insulating material separating the ends of said strip; a rheostat mounted on said sector; and an electric circuit connecting in series one end of said strip, said shoe and said rheostat, substantially as described.

2. In a controller, the combination of circular strip of conducting material of high resistance; a controller-arm mounted to rotate on a pivotal axis concentric with said strip, said arm being insulated at the center from the strip and having thereon a shoe having electrical connection with the strip; a sector of insulating material separating the ends of said strip; a rheostat mounted on said sector and having an annular series of contact-buttons connecting a series of resistance-coils; a disk rotatably mounted on the sector coneentrieally of said contact-buttons and covering the same but insulated therefrom, said disk having thereon a part adapted to bear on one of said buttons at a time, an indicator for showing the position of said part relatively of the series of buttons, and an electric circuit connecting said rheostat in series with said arm and strip, substantially as described.

3. In a controller, the combination of a circular strip of conducting material of high resistance; a controller-arm mounted to rotate on a pivotal axis concentric with said strip, said arm being insulated at the center from the strip and having thereon a shoe having electrical connection with the strip; a sector of insulating material separating the ends of said strip; a rhcostat mounted on said sector and having an annular series of contact-buttons connecting a series of resistance coils; a disk rotatably mounted on the sector concentrically of said contact-buttons and covering the same but insulated therefrom, said disk having thereon a part adapted to bear on one of said buttons at a time and said disk having thereon annular graduation corresponding to said buttons; a pointer on said sector to indicate the position of said part; and an electric circuit connecting said rheostat in series with the strip out of the circuit when the arm is in contact with the stop, substantially as described.

Signed at Chicago this 5th day of December, 1904.

FRED CEDERGREN.

Witnesses:

NELs A. STRAND, EUGENE A. RUMMLER. 

